Nanoprocessing of Industrial Rejects for Controlling Operational Energy of Buildings

This study investigates the pozzolanic potential of industrial waste, which fails to meet the chemical composition as defined by the various international standards, e.g., IS: 3812 (Part 1): 2017 and ASTM C618-19 to adopt as a supplementary cementitious material. The effects of mechanical nanoprocessing on pozzolanic reaction efficiency, impact on energy efficiency, and construction affordability were studied. The result of mechanical milling shows the improvement in pozzolanicity, and the physicomechanical characteristics of novel concrete incorporated with identified industrial waste are comparable with control concrete. The building energy simulation was carried out using the BIM software for the house, modelled with controlled concrete, and novel concrete incorporating the identified milled industrial waste. The peak cooling load and building material cost of a novel concrete model house were 34% and 9.09% less than the conventional concrete. The study reveals that the chemical characterization provided in international standards shall not be the only criteria to decide the suitability of the materials to use as supplementary cementitious material, whereas the same can be examined and improved through various treatments, and mechanical nanoprocessing may be one of the best options. Cement production and utilization affect the environment. To reduce the concern, pozzolanic investigation of industrial waste is necessary, which can address the issue of uncontrolled extraction of natural resources, emission, disposal, and pollution globally. the can a as and study of BIM tool to the innovative for consumption, life cycle analysis, and time cost analysis for the studies. overall results mechanical milling may not the of it can the and physical for the concrete after a mix and trials. This can also be adopted of and


Introduction
Industrialization in developing countries has resulted in the consequent accumulation of unmanageable industrial wastes and greenhouse gases (GHGs). Asia produces 4.4 billion tons of solid waste every year [1]. As per the United Nations Environment Programme (UNEP) report, 86 billion tons of carbon dioxide are emitted by global buildings annually [2]. Presently, India alone generates about 290 million tons (MT) of inorganic wastes [3] and 76.4 MT of CO 2 [4] per year from various cement manufacturing industries. Normally, 0.9 ton and 0.1 ton of CO 2 are released into the environment during the manufacturing of 1 ton of cement and 1 ton of concrete, respectively [5,6]. Cement production (∼550 MT by 2020-21) [7]and consumption in India have increased multifold in the last few decades [8].
e exponential production and consumption of cement and cement products creating a huge environmental burden with the exploitation of natural resources are becoming a global issue [9]. e application of limestone during the clinkering process results in a signi cant amount of emissions (5-6% of total greenhouse gas emissions) [10][11][12] by consuming a huge amount of nonrenewable resources [7,13]. Around 350 to 540 kg of raw slag is generated, from the per ton production of liquid iron and steel [14,15], and around 24 MT of slag is generated every year in India [16]. e state-wise annual production of steel and iron slag in India is shown in Figure 1.
In the twenty-rst century, nanotechnology was a highly adopted technology for research and development in construction worldwide [19]. e nanoparticles/nanocomposites have attracted considerable attention as structural materials, because of their low density, high specific modulus, strength, and resistance to wear and corrosion [20]. However, the application of nanotechnology in the development of alternate construction materials needs to be studied in detail. Similarly, energy analysis and cost-effectiveness are also required to be studied for the building energy simulation of alternate nanomaterials [21]. Building information modelling (BIM) is an effective simulation tool that can undertake these parameters [22]. BIM enables the user to create a virtual model to simulate the planning, design, construction, and operational facility in the building [23]. BIM results are object-oriented, intelligent, and provide the digital data of building facilities, generating information on thermal and functional performance, which help to improve the decision and process of establishing the facilities [24,25]. BIM regulates the life cycle cost, design, construction, and operational cost of a project [15][16][17].
Many researchers investigated the thermal performance and embodied energy of building components using the BIM software tool (Revit 2019). e thermal performance of various construction materials developed incorporating industrial wastes was investigated by various researchers using Revit 2019 and is tabulated in Table 1.
Now, there is a need of an hour to find sustainable alternatives to primary binding material (cement) from the enormous available industrial rejects. However, such studies have limitations on the obtained oxide compositions, the particle size of waste material, and their suitability as SCM in accordance with BIS 3812 (Part 1): 2017 [32]. e pozzolanic material not only helps to decrease the burden on natural resources but also encourages to decrease the carbon emission of cement and concrete production. e pozzolanic efficiency of unsuitable industrial waste (as per IS 3812 (Part 1): 2017)   Note. GF-ground floor, Ext-external wall, Int-internal wall. was examined after nanoprocessing, i.e., mechanical milling from high-energy ball mill. Introducing the nanotechnology for material milling was found to be an effective treatment to make industrial waste suitable to use as a SCM. In addition to that, the energy efficiency and cost of effectiveness of prototype model were analysed using BIM tool.

Materials and Methods
e investigation process is depicted in Figure 2, which explains the step-by-step methodology used in this study. An industrial waste was identified, which was easily available in and around the study area. Further, the properties of raw materials were identified using the physicochemical and physicomechanical tests and the suitability was checked to use a SCM/pozzolana. If the material fails to meet the criteria to use as a pozzolana, then it must be suitably treated with the best economical option. In this study, mechanical milling treatment was adopted where the material was ground to nanoscale. Subsequently, the properties of milled samples were again tested for pozzolanic efficiency. e treated material with improved pozzolanic efficiency was used for the product development, and later, the performance and affordability of building developed with various building Step 1 Step 2 Step 4 Step 3 Step 5 Pass Pass Pass Pass Figure 2: Flow diagram for the methodology adopted for the experimental work. Advances in Civil Engineering 3 applications incorporating the treated milled material were analysed using BIM tool.

Materials Used.
Granulated blast furnace slag (GBFS), an industrial waste, was considered as the principal raw material for the study, which was collected from the iron and steel industry available in and around the research area (Nagpur, Maharashtra, India). OPC 53 grade cement conforming to IS: 12269-2013 [33] was used as a primary binder for laboratory trials. Locally available river sand and crushed stone conforming to IS: 383-2002 [34] were used as fine and coarse aggregates. To perform pozzolanicity tests, necessary chemicals such as saturated calcium hydroxide (Ca(OH) 2 ) solution, calcium oxide (CaO), distilled water, phenolphthalein indicator, the concentrated and 0.1 N hydrochloric acids (HCl), concentrated nitric acid (HNO 3 ), concentrated sulfuric acid (H 2 SO 4 ), hydrofluoric acid (HF), and Whatman filter paper no. 40 were used.

Methodology Adopted.
To pulverize the principal raw material to the nanoscale, a high-energy planetary ball mill (Fritsch Pulverisette P5) was used. Milling was optimized using differential time duration of 10, 30, and 90 minutes, i.e., GBFS 10, GBFS 30, and GBFS 90. Figure 3 represents the proposed raw materials, i.e., GBFS, before and after milling. e physical characterization of the material was carried out as per IS 1727-2004 [35]. e physical properties such as specific gravity, bulk density, and setting time of GBFS were tested as per the relevant Indian standards. e nanostructure analysis of identified material was evaluated by particle size distribution (PSD) [36,37], scanning electron microscopy (SEM) [38,39], X-ray diffraction (XRD) [40,41], and X-ray fluorescence (XRF). Grading of mechanically treated ultrafine ground fraction raw materials (granulometric analysis) was performed using a laser particle size analyser [42]. e liquid media was used to conduct the analysis [43]. e ultrasonic frequency was 80 Hz, and the pump speed was 600 rpm. After 10-12 minutes, particle size was assessed. Surface morphology and particle size resemblance of the samples were inspected using the Scanning Electron Micro-Probe Analyzer-JEOL, JAPAN JXA-840. e chemical oxide compositions and loss of ignition (LOI) were evaluated using PANalytical "PW2403 MagiX" XRF technique. Xpert-PRO X-ray diffractometer system was used to analyse the mineral phases of raw and milled material.
An electrical conductivity test is conducted to study the pozzolanicity of supplementary cementitious materials (SCMs). e sample was prepared using the identified material and calcium hydroxide solution. e water and sample solution was used to find the conductivity of ions present in the material [55,56]. e Chapelle activity test was performed to determine the fixed CaOH by taking the solution of grounded material in water with CaO and titrating the same with HCL and using phenolphthalein solution as an indicator [54,55,57].
where V 1 is the volume of HCL consumed for titrating solution without pozzolana. V 2 is the volume of HCL consumed for titrating solution containing pozzolana. e suitable building application was developed as an end product using milled GBFS samples and compared over the conventional building application of the same grade for energy efficiency using the BIM simulation tool.

Model Development
After the micro-analysis of identified material, the pozzolanic performance of mechanically milled material was evaluated to check the sustainability of materials and treatment process. On suitability of materials, a novel construction concrete building application was cast incorporating the mechanically milled (treated) industrial waste, and later, a model house was simulated in BIM software for conventional and novel concrete elements to study the energy efficiency and affordability. BIM tool is used for 3D design and modelling, which helps in forecasting the building design, assembly of elements, and work progress [40,41]. A single-storey residential building was selected for BIM model. e project was situated in Indore, Madhya Pradesh, under the lightweight housing scheme of Global Housing Technology Challenge (GHTC), Government of India. e project aims to provide a sustainable technology solution for faster and cost-effective construction suitable for the geo-climatic zones and hazardous conditions. Figure 4 shows the 2D plan of building, and Autodesk AutoCAD 2019 version was used to draw the plan. e plan of a single dwelling unit has an area of 29.92 m 2 . e carpet area was also approved by the GHTC, India [58]. e prototype model of the same project was analysed for the study area, Nagpur, Maharashtra, India (latitude 21.1311⁰N and longitude 79.0511⁰E). e residential building mainly consists of three rooms, i.e., living room, a bedroom, and a kitchen with a small passage and toilet. Clear 3 m height of the unit was considered. e thickness of the exterior and internal walls was considered 150 mm and 100 mm, respectively. ree windows, W1, W2, and W3 of sizes 1.5 m × 1.2 m, 1m × 1.2 m, and 0.8 m × 1.2 m, respectively, were provided. e doors D1, D2, D3, and D3A of size 1.2 m × 2.1 m, 1m × 2.1 m, 0.75 m × 2.1 m, and 0.9 m × 2.1 m, respectively, were provided in the building. For the base case, the model developed with elements of conventional concrete was considered, whereas the alternate model developed with building application of the same grade incorporating milled GBFS was considered for comparative analysis. e peak cooling load demand was calculated for both the models. e temperature range of 18-28°C for the climate zone of Nagpur (21.1311°N-79.0511°E) was set as per the SP 41 (BIS-1987) [59]. Each room of the building was analysed for the design cooling load using the building information modelling tool (BIM) that is the Revit Architecture 2019 Student Version [60]. Two separate models were simulated for analysis where the walls, floor, and slab of the building were considered with the properties of respective materials.

Results and Discussion
e results of the tests performed on as-received and mechanical-processed industrial waste are discussed as follows.

Physical Properties.
e results of the physical characterization are shown in Table 2. From the test results, it was observed that the specific gravity of industrial waste before and after milling remains unchanged and was found lower than the specific gravity of cement; hence, it was expected that the building material incorporating these wastes will be lighter in weight. e density of material was determined before and after milling; there was no discernible difference observed in the density of GBFS after milling. e initial setting time of the proposed industrial waste was higher than the cement, whereas the final setting time is lower than the cement, which is further diminished significantly on milling.
e surface area of industrial waste increases exponentially on milling.
e negligible evidence of soundness and shrinkage percentage was noticed before and after milling; hence, it can be recommended for suitable building applications. Milled GBFS showed considerable improvement in lime reactivity.
In Table 3, characteristics of before (0 min) and after milled (90 min) GBFS are displayed according to the criteria mentioned in Table 2 of BIS 3812 (Part 1): 2017. e comparative study was carried out on basis of fineness: wet sieving, lime reactivity strength, 28 days of compressive strength, and soundness of material. 126% improvement in fineness was noticed after milling the sample than that of the before milled sample and meeting the requirement of BIS. Particles retained on 45 micron IS sieve using the wet sieving method before and after milling show the result of 24% and 100%, respectively, whereas the minimum requirement is 34%. e improvement in fineness must be the result of the mechanical nanoprocessing. e lime reactivity of milled samples improves significantly after mechanical milling and achieved 85% more strength than the BIS, i.e., IS 3812 (Part 1): 2017. e compressive strength of milled samples was increased by more than 100%. e observed improvement is due to the particle packing and well compaction of nanoparticles. Negligible soundness was observed before and after milling, which shows the suitability to mix the material in principle binding material cement for various building applications/products. Table 4 shows the chemical composition of the proposed industrial waste. It was observed that the milling treatment had no discernible influence on the chemical compositions and LOI values of the materials.

X-Ray Fluorescence (XRF).
e amorphous (% reactive) silica plays a major role in the pozzolanic activity of the materials as per the provisions prescribed by BIS 3812 (Part 1): 2017. From the obtained results of XRF, it was observed that the industrial waste, i.e., GBFS, fails to meet the criteria mentioned in Table 1, BIS 3812 (Part 1): 2017, and hence, it is not suitable for the use as supplementary cementitious material even though the LOI is within the acceptable range as prescribed by the same BIS. e criteria given in BIS for the combined percentage of Al, Si, and Fe were also not satisfied by the GBFS milled sample. Figure 5 shows X-ray diffraction analysis of as-received and milled samples of GBFS.

X-Ray Diffraction (XRD).
e graph was plotted diffraction angle (2θ) versus intensity count, where the diffraction angle was stated from 10-degree angle and raised up to 70°on x-axis. e intensity of peaks for as-received sample and optimized milled sample (90 min grinding duration) was started from 140 counts and 150 counts, respectively, and this shows that the GBFS absorbed the energy on milling. Graphs A and B show the XRD phase of as-received and milled GBFS. e flattered hump between 20°and 35°diffraction angle and intensity depicts the amorphous phase of an as-received and milled sample of GBFS. ere is no significant change observed in the XRD phase before and after milling of GBFS. Hence, as-received and milled GBFS was expected to participate in hydration reaction due to the presence of amorphous silica. Figure 6 shows the surface morphology and particle size resemblance measured by scanning electron microscopy (SEM). e image shows the particle agglomeration after the high-energy milling Advances in Civil Engineering process, even after individual particle size reached the nanoscale range. e particle size increased due to the agglomeration was highlighted in yellow circle, which shows the deposition of more than one particle. is agglomeration temporary occurs because of the van der Waals force of attraction, in which particle is obtained after high-energy milling. erefore, the values after final milling, i.e., 30 min and 90 min of material, show the enlargement in size of particles. GBFS was milled for 90 minutes and resulted in particles of sizes ranging from 50 to 600 nm, respectively. Figure 7 represents the laser particle size distribution of proposed industrial rejects. e size of particle scales on D 10 (10% particles passing), D 50 (average passing), and D 90 (90% particles passing) is depicted in Table 5, respectively. e as-received sample was milled for 10, 30, and 90 minutes in a high-energy planetary mill to bring it to nanolevel. Insignificant variation in the particle size was observed after milling for 10 to 30 min of duration. e average particle size of as-received sample was observed to be 331 nm on 10 min of milling and the sample size was observed to be 344 nm, whereas on 30 min of milling the sample size was observed to be 328 nm; this may be due to the surface charge increments in particles. After that, a large reduction in the particle size was observed for a milling duration of 90 min. e D 50 of agglomerated GBFS (i.e., GBFS-WM) shifted to 384 nm from 331 nm on 90 min of milling. It was observed that the enlarged surface area after milling is due to van der Waals force of attraction or surface charge, in which particles acquire after milling. erefore, the values of the final grinding, i.e., 90 min of GBFS, show the increment in size of particle, which is reflected in Table 5.  Figure 4: AutoCAD 2D plan for single dwelling unit. Advances in Civil Engineering industrial wastes to be considered as SCM. e pozzolanicity tests were performed before and after milled material to study the effect of mechanical processing on pozzolanic properties.

Pozzolanic Activity Index (PAI)-Strength
Determination. e observed compressive strength and the trends of compositions established with the effect of milling are shown in Table 6 and regression patterns as shown in      e PAI method was adopted as specified in Brazilian standard NBR 12653:1990 for the pozzolanic material testing. e R 2 values obtained from the regression (Figure 8) show the significant improvement in the pozzolanic rate of reaction in GBFS on milling.

Electrical Conductivity Test (ECT).
To evaluate and ensure the material's pozzolanic reactivity, an electrical conductivity test was also performed. e electrical conductivity of saturated Ca(OH) 2 at 40 ± 1°temperature was 7.98 mS/cm noticed. e concentration of calcium and hydroxyl ion reduces with time, which could be noticed from the decrement in conductivity values of GBFS solution. e results reveal the reaction between the silica present in GBFS and the Ca(OH) 2 standard solution, which formed the C-S-H gel. e R 2 value obtained from the regression (Figure 9) for GBFS was 0.96, which shows the significant improvement in pozzolanic rate of reaction due to mechanical milling.

Chapelle Activity Test.
Chapelle activity is carried out to evaluate the consumed Ca(OH) 2 in the pozzolanic reaction. Pozzolanic material is added to the hydrated cement paste, so that silica reacts with the Ca(OH) 2 to produce secondary C-S-H gel [43]. e larger surface area of pozzolanic material increases the rate of pozzolanic reaction, and the amount of reaction produces secondary C-S-H gel. Figure 10 shows the trend of the Chapelle activity for GBFS. A significant increase in the consumed Ca(OH) 2 was observed due to the milling treatment for all the samples. e best results were fitted in the linear mathematical model. e R 2 value obtained for GBFS is 0.983. e observed regression model was significant and effective, as the R 2 value was close to 1, whereas, from Table 6, it was observed that the Chapelle activity of GBFS was better than the standard values. Chapelle

Performance and Affordability Evaluation
A comparative study carried out by Azhar et al. [24] for analysis of building performance revealed that the virtual environment is the most powerful and versatile software tool followed by Ecotect and Green Building Studios. Shoubi et al. [60] used Revit Architecture and Ecotech for energy analysis of building having an area of 400 m 2 twostorey unit where the composite material was proposed for saving operations energy of buildings. Gavali et al. [28,29,61] simulated a single-storey load-bearing model in Nagpur, India. e products were developed incorporating the co-fired blended ash (CBA) and fly ash bricks.
e analysis was carried out using Revit Architecture BIM tool. e analysis concluded that deploying CBA bricks in construction would potentially lower the cost and energy of the building in comparison with fly ash brick. e above discussion emphasized and justified the use of the BIM tool for assessing the thermal performance, energy analysis, and affordability of buildings [64]. Hence, the Revit Architecture 2019 (Student Version) simulation tool was used for energy analysis and affordability study.
Models were simulated for a design mix of M30 grade concrete. e base model was considered with conventional concrete using OPC 53, and the alternate model was with replacing the 30% of OPC by milled GBFS industrial waste. e model is shown in Figure 11. e concrete made up of industrial waste was tested for physicomechanical properties after 28 days of wet curing. e physicomechanical properties show the desirable results over the conventional concrete.
e density of concrete made from GBFS was noticed as 0.8% lower than control concrete, and this shall be due to the decreased specific gravity of GBFS (10%) when compared with OPC. To evaluate the energy analysis of the models, the thermal conductivity of GBFS concrete was examined as per the IS 9489:2017 [62]. e thermal conductivity of GBFS concrete is observed 34.3% lower than control concrete of the same grade.
For building simulation, the product properties need to be incorporated into the BIM software such as thermal conductivity and density. e simulation resulted in space heating and cooling load inside the dwelling unit, where the peak cooling load was estimated for the individual model. All elements of the dwelling unit were considered with the same material properties for slab, floor, and walls. e peak cooling load of GBFS model was found 34% lower than the base model cast with control concrete. e significant change was noticed in the results of the functional analysis of GBFS over control concrete. Also, a noticeable variation was observed in the affordability analysis. BIM software revealed that the total concrete volume for the single-family unit is 11.42 m 3 . e cost of concrete ingredients was based on current and prevailing market rates near the research area. e energy cost of mechanical milling was considered in case of concrete applications incorporating industrial waste. e mechanical milling of industrial waste requires an energy of 0.0043 MJ/kg. e cost of transportation, labour, and equipment in both the cases are locationspecific and equivalent hence not considered for cost analysis.
e BIM models show that the cost of GBFS concrete is 9.09% lower than the cost of control concrete. Table 7 shows the comparative study of material along with thermal properties.

Conclusions
e aim of this work was to compare the operational energy of a building developed with novel materials incorporating nanoprocessed industrial waste, which was unsuitable to use as SCM over the conventional material. In the first part of this study, the pozzolanic performance is evaluated of nanoprocessed industrial waste where the appropriate direct and indirect pozzolanicity tests are used.
e results obtained from the tests show that the treatment has a potential to make non-SCM to active mineral admixture. e mechanical milling of GBFS for the optimized duration of 90 minutes, respectively, reduces the particle size of GBFS up to nanolevel, which increases the surface area of the material by 226% with a subsequent increase in the pozzolanic rate of reaction. SEM showed an increase in particle size of identified industrial waste in mechanical milling due to the phenomenon of agglomeration. GBFS meets the requirements of SCM as per the IS 3812: 2013 except for silica percentage. e pozzolanic performance was evaluated from the obtained results of the pozzolanic activity index (PAI), Chapelle activity (CA), and electrical conductivity (EC). e GBFS PAI meets the strength requirements at optimized duration. e results of the Chapelle activity showed that the amount of Ca(OH) 2 consumed in milled GBFS is 224.99% as compared to as-received GBFS. e milled GBFS sample showed the better pozzolanic performance by 21% compared with the criteria mentioned in NFP 18-513. e identified materials (GBFS) showed a significant electrical conductivity drop when tested for pozzolanicity. e electrical conductivity drops for milled GBFS increased by 10% compared with as-received sample. e linear regression models of the pozzolanic activities and milling duration were established. e R 2 values of PAI, CA, and EC test of GBFS have a range of 0.70-0.99 for all pozzolana tests. e ultrafine particles of GBFS significantly improve pozzolanicity. is could lead to the maximum replacement of cement in concrete production. Ultimately, it will reduce greenhouse gas emissions and will help the cement industry to become more sustainable. Furthermore, it will provide the solution to the problem of waste disposal and pollution.
In the second part, BIM tool was used to develop the simulation model and evaluate the energy performance and cost analysis of material. e BIM tool evaluated the operational peak cooling and heating load of material after simulation. e main sources of energy efficiency of building were external walls, windows, and doors, which are foist heating and cooling load on structure. BIM tool offers the opportunity to connect all particulars of building to measure operational energy consumption, cost of building components with treated material, etc. is method can be adopted for any building to calculate the load on elements of structure by selecting the alternative material, which reduced the energy consumption and environmental impact. e critical analysis result shows the performance study of Industrial rejects GBFS consisting of low thermal conductivity as compared to control concrete. e peak cooling Using industrial waste, the cost of construction was reduced by 9% to conventional building cost, and it was observed that the GBFS can give a more effective solution as a sustainable and economical material. is study encourages the utilization of BIM tool to analyse the innovative materials for the energy consumption, life cycle analysis, and time cost analysis for the future studies. e overall results reveals that the mechanical milling may not improve the chemical characteristics of material, but it can enhance the pozzolanicity and physical properties of wastes. erefore, such milled industrial wastes can be a promising material for the concrete manufacturing after designing a mix and trials. is material can also be adopted as the alternative of cement, which can reduce the carbon footprints and energy emission and prove the affordable materials for the future construction industry.

Abbreviations
Al: Aluminium Al 2 O 3 : Aluminium oxide BFA: Bio-fuel ash BIS: Bureau of Indian Standards BIM: Building information of modelling CA: Chapelle activity CaOH 2: Calcium hydroxide CBA: Co-fired blended ash CO 2

Data Availability
Data statements will be made available whenever required.

Additional Points
(i) Mechanical milling was used for nanoscaling of identified industrial waste. (ii) e pozzolanic properties of industrial waste were improved through nanoscaling. (iii) e building energy simulation was studied using the BIM tool. (iv) Peak cooling load and building cost is 34% and 9.09% lower than conventional ones.

Disclosure
Statement of Novelty. In this research, an industrial waste that fails to meet the pozzolanic criteria, as per the BIS 3812 (Part 1): 2017 and ASTM C618-19, was selected. e pozzolanicity results were validated and statistically established through various available pozzolanicity test methods and microstructure analyses. Also, a holistic approach is adopted by assessing the energy and cost efficiency of modelled building unit developed by incorporating treated industrial waste over the conventional through building information modelling (BIM) tool. is shall lead to a new pathway to utilize the industrial rejects as a partial replacement of the cement in construction industry, which will reduce the carbon emission of cement industry.

Conflicts of Interest
e authors declare that they have no conflicts of interest.